Milo: Add themed page for errors

milo/appengine/buildbot/build_test.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package buildbot
 
 import (
         "encoding/json"
         "flag"
         "fmt"
@@ skipping 65 matching lines @@
                         })
                 }
 
                 Convey(`Disallow anonomyous users from accessing internal builds`, func() {
                         ds.Put(c, &buildbotBuild{
                                 Master:      "fake",
                                 Buildername: "fake",
                                 Number:      1,
                                 Internal:    true,
                         })
-                        b, err := getBuild(c, "fake", "fake", 1)
-                        So(b, ShouldBeNil)
+                        _, err := getBuild(c, "fake", "fake", 1)
                         So(err, ShouldResemble, miloerror.Error{
                                 Message: "Cannot fetch project buildbot-internal:\ndatastore: no such entity",
                                 Code:    500,
                         })
                 })
         })
 }